Issues with cycling tank

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lizerdking

lizerdking

Gambusia
MFK Member
Dec 30, 2014
138
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18
west coast
So i have been cycling a 240 gallon tank for over a month now but im still showing. 05 ammonia. Initially the tank seemed to be cycling as normal, nitrites shot up ammonia went down. But for the last three weeks nothing no nitrit,e low nitrates and .05 of ammonia. Im running a fx6 i have 6 minnows in there, and i add some market shrimp about once a week. I also try to change water twice a week. Any ideas?
 
Minnows probably arent producing enough waste to keep the bacteria alive. I would take them out and start a fresh fishless cycle. If you do have some bacteria going, it shouldnt take too long to get a real cycle going.
 
Cycling a tank involves growing a large enough population of bacteria, to convert the ammonia to less toxic nitrate. This does not happen over night, or even in a month. A true cycle can take 3 months in a tank of 200+ gallons, unless you've added seasoned substrate or media.
 
duanes said:
Cycling a tank involves growing a large enough population of bacteria, to convert the ammonia to less toxic nitrate. This does not happen over night, or even in a month. A true cycle can take 3 months in a tank of 200+ gallons, unless you've added seasoned substrate or media.
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It did a fish less cycle for three months to make sure it was cycled in my 200 gallon tank. Better safe than sorry. Also I didn't immediately just add tons of fish I slowly did didn't want the cycle to crash with crazy bio load.

Keep doing what you're doing eventually it will be cycled. It's 10 times faster if you had media from before seeding but not everyone has that
 
I'll make some assumptions in fill in the needed information, but feel free to correct it.

1) you have 6 minnows in a 240 gallon tank. I assume they are each around 2.5" for this discussion. That's a total of 11 grams of fish. Assuming they are also fed (also not mentioned) at 3% body weight per day, with 35% protein 90% dry weight food, that would generate ~ 0.05 ppm nitrates per day.

2) you are adding market shrimp each week. There was no mention of how many or what size, so I'll assume 2 per week, at around 11 grams in size each. Shrimp are ~83% protein and 59% water, so that works out to ~3.8 ppm of nitrate per week.

So that works out in total to ~4 ppm nitrates per week. Since you are doing water changes (of an unstated amount), you will indeed have virtually no nitrates after 6 weeks.

Your readings on ammonia and nitrite probably depend on when you take them. If its within 24 hours of the shrimp being fed they could be high. At any other time it would generate negligible readings. I calculate 0.01 ppm of ammonia and 0.04 ppm of nitrite.

In the linked thread on fishless cycling, it's recommded that one add 5 drops of ammonia (.41 grams) for every 10 gallons of water each day. In a 240 gallon tank, that would be 9.6 grams per day on average. By my estimates above, you are adding .3 grams per day.

According to my assumptions (again, they are merely assumptions) you have inadequate imput. My guess it that most of the original bacteria has been lost, but that's again, an assumption.
 
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Drstrangelove said:
I'll make some assumptions in fill in the needed information, but feel free to correct it.


1) you have 6 minnows in a 240 gallon tank. I assume they are each around 2.5" for this discussion. That's a total of 11 grams of fish. Assuming they are also fed (also not mentioned) at 3% body weight per day, with 35% protein 90% dry weight food, that would generate ~ 0.05 ppm nitrates per day.

2) you are adding market shrimp each week. There was no mention of how many or what size, so I'll assume 2 per week, at around 11 grams in size each. Shrimp are ~83% protein and 59% water, so that works out to ~3.8 ppm of nitrate per week.

So that works out in total to ~4 ppm nitrates per week. Since you are doing water changes (of an unstated amount), you will indeed have virtually no nitrates after 6 weeks.

Your readings on ammonia and nitrite probably depend on when you take them. If its within 24 hours of the shrimp being fed they could be high. At any other time it would generate negligible readings. I calculate 0.01 ppm of ammonia and 0.04 ppm of nitrite.

In the linked thread on fishless cycling, it's recommded that one add 5 drops of ammonia (.41 grams) for every 10 gallons of water each day. In a 240 gallon tank, that would be 9.6 grams per day on average. By my estimates above, you are adding .3 grams per day.

According to my assumptions (again, they are merely assumptions) you have inadequate imput. My guess it that most of the original bacteria has been lost, but that's again, an assumption.
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Impressive breakdown my friend, what do you recommend?
 
http://www.monsterfishkeepers.com/forums/threads/fishless-cycling.28654/

Here is a great write up, although there have been good summaries given by many people else where. Also there are several other stickies in the same spot (See "Setup and Filtration forum, find the sticky about cycling.)

Unless time is factor, I would start with where you are, and begin adding pure ammonia (3 drops per 10 gallons will give ~3 ppm readings on ammonia in a 240 gallon tank.) The process will be quicker than the write-up because I think it's certain that you have BB colonies, but they are merely small.

Another option is to add BB directly (many people do that and it's effective.)

Also, it's probable that you are close to done----if an only if----your plan is to start the tank with a few very small fish. The problem is that if you plan to start with 10-12 fish that are 6-8" or larger in this tank, that the BB are woefully inadequate. The current bio capacity is pretty small.

Some people simply add BB to the tank, but that isn't what I do, so I'll let them explain that process.
 
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